From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 29D2D26462E for ; Mon, 21 Apr 2025 12:19:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745237992; cv=none; b=Vp4QKC7cUt4XRNkIwsOVByKczUqfTTVypzgm5ElXh8FEVNbvajMKK1Tzo73yxs1HUJ3Is7Rke6cL80aUXVAzSFhaHFgvGzT4QEWEOaC8DELFUZip2esU+t9EobX1bsTU21I2v8gJTdPjVckGoYrvDqhSAnGNaJxEd/CpSPiqYzs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745237992; c=relaxed/simple; bh=3WXQwHetCzvpTvunxuXtwwTlyHhRUHSOawU70PTDMwA=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=ayP4SnHJb4zpbbeU0AB2vW80C/srqyzH2AYn0Q7fOwf9E0KeXL4k9AZLyzsz0M/n3Afx16cHJVjZ2D2IhYiYURFN0CKFYSiWZh/kTkt2Kb1U9gnOM5lDjXI7sGzNTejzjMaF99+2fAOqMYpldX2rI6DjwpPaX8jHR1EdoiGvnNM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VOz4AUb8; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VOz4AUb8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E4646C4CEE4; Mon, 21 Apr 2025 12:19:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745237991; bh=3WXQwHetCzvpTvunxuXtwwTlyHhRUHSOawU70PTDMwA=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=VOz4AUb8scDOulPn75K6FAvdflF4o++8DXit9PA4+ssr2I/YZ5sbgekxpQgKVqyuR TcJSiHMCO9/mVa5S7aCn/ba+D9hCC7lwEHsqq251T72PgQuBW87VWLJOBMoFoBLL/z bDwk/BpsRPjCHhRc4HqqA/eC3YEXKJfoMxemkrX7tyiRLoj5L4QaLuo6jbqZ3VE8dy 4epKUQyjBgFvIoH8BGmFLaZmQowD1w9jWnbX/hrLcxN4i+kRVmlJz/qZ7oU4FeBHhJ lEIa+n6Qy3L7c8L5xfD+//LMbUl036ul9eNyUzELJutDUbFOjD+TdPU1IUeQdyBFyI pQcuxo+IYc3yw== Message-ID: <8c89fc483efdb0b5eab660781416cba500e54b64.camel@kernel.org> Subject: Re: [PATCH v2 03/10] sunrpc: Replace the rq_pages array with dynamically-allocated memory From: Jeff Layton To: cel@kernel.org, NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: linux-nfs@vger.kernel.org, Chuck Lever Date: Mon, 21 Apr 2025 08:19:49 -0400 In-Reply-To: <20250419172818.6945-4-cel@kernel.org> References: <20250419172818.6945-1-cel@kernel.org> <20250419172818.6945-4-cel@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Sat, 2025-04-19 at 13:28 -0400, cel@kernel.org wrote: > From: Chuck Lever >=20 > As a step towards making NFSD's maximum rsize and wsize variable at > run-time, replace the fixed-size rq_vec[] array in struct svc_rqst > with a chunk of dynamically-allocated memory. >=20 > On a system with 8-byte pointers and 4KB pages, pahole reports that > the rq_pages[] array is 2080 bytes. Replacing it with a single > pointer reduces the size of struct svc_rqst to just over 9500 bytes. >=20 > Signed-off-by: Chuck Lever > --- > include/linux/sunrpc/svc.h | 3 ++- > net/sunrpc/svc.c | 34 ++++++++++++++++++------------- > net/sunrpc/svc_xprt.c | 10 +-------- > net/sunrpc/xprtrdma/svc_rdma_rw.c | 2 +- > 4 files changed, 24 insertions(+), 25 deletions(-) >=20 > diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h > index 5b879c31d7b8..96ac12dbb04d 100644 > --- a/include/linux/sunrpc/svc.h > +++ b/include/linux/sunrpc/svc.h > @@ -200,7 +200,8 @@ struct svc_rqst { > struct xdr_stream rq_res_stream; > struct page *rq_scratch_page; > struct xdr_buf rq_res; > - struct page *rq_pages[RPCSVC_MAXPAGES + 1]; > + unsigned long rq_maxpages; /* num of entries in rq_pages */ > + struct page * *rq_pages; > struct page * *rq_respages; /* points into rq_pages */ > struct page * *rq_next_page; /* next reply page to use */ > struct page * *rq_page_end; /* one past the last page */ > diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c > index 8ce3e6b3df6a..682e11c9be36 100644 > --- a/net/sunrpc/svc.c > +++ b/net/sunrpc/svc.c > @@ -636,20 +636,25 @@ svc_destroy(struct svc_serv **servp) > EXPORT_SYMBOL_GPL(svc_destroy); > =20 > static bool > -svc_init_buffer(struct svc_rqst *rqstp, unsigned int size, int node) > +svc_init_buffer(struct svc_rqst *rqstp, const struct svc_serv *serv, int= node) > { > - unsigned long pages, ret; > + unsigned long ret; > =20 > - pages =3D size / PAGE_SIZE + 1; /* extra page as we hold both request a= nd reply. > - * We assume one is at most one page > - */ > - WARN_ON_ONCE(pages > RPCSVC_MAXPAGES); > - if (pages > RPCSVC_MAXPAGES) > - pages =3D RPCSVC_MAXPAGES; > + /* Add an extra page, as rq_pages holds both request and reply. > + * We assume one of those is at most one page. > + */ > + rqstp->rq_maxpages =3D svc_serv_maxpages(serv) + 1; > =20 > - ret =3D alloc_pages_bulk_node(GFP_KERNEL, node, pages, > + /* rq_pages' last entry is NULL for historical reasons. */ > + rqstp->rq_pages =3D kcalloc_node(rqstp->rq_maxpages + 1, > + sizeof(struct page *), > + GFP_KERNEL, node); > + if (!rqstp->rq_pages) > + return false; > + > + ret =3D alloc_pages_bulk_node(GFP_KERNEL, node, rqstp->rq_maxpages, > rqstp->rq_pages); > - return ret =3D=3D pages; > + return ret =3D=3D rqstp->rq_maxpages; > } > =20 > /* > @@ -658,11 +663,12 @@ svc_init_buffer(struct svc_rqst *rqstp, unsigned in= t size, int node) > static void > svc_release_buffer(struct svc_rqst *rqstp) > { > - unsigned int i; > + unsigned long i; > =20 > - for (i =3D 0; i < ARRAY_SIZE(rqstp->rq_pages); i++) > + for (i =3D 0; i < rqstp->rq_maxpages; i++) > if (rqstp->rq_pages[i]) > put_page(rqstp->rq_pages[i]); > + kfree(rqstp->rq_pages); > } > =20 > static void > @@ -704,7 +710,7 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_= pool *pool, int node) > if (!rqstp->rq_resp) > goto out_enomem; > =20 > - if (!svc_init_buffer(rqstp, serv->sv_max_mesg, node)) > + if (!svc_init_buffer(rqstp, serv, node)) > goto out_enomem; > =20 > rqstp->rq_err =3D -EAGAIN; /* No error yet */ > @@ -896,7 +902,7 @@ EXPORT_SYMBOL_GPL(svc_set_num_threads); > bool svc_rqst_replace_page(struct svc_rqst *rqstp, struct page *page) > { > struct page **begin =3D rqstp->rq_pages; > - struct page **end =3D &rqstp->rq_pages[RPCSVC_MAXPAGES]; > + struct page **end =3D &rqstp->rq_pages[rqstp->rq_maxpages]; > =20 > if (unlikely(rqstp->rq_next_page < begin || rqstp->rq_next_page > end))= { > trace_svc_replace_page_err(rqstp); > diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c > index ae25405d8bd2..23547ed25269 100644 > --- a/net/sunrpc/svc_xprt.c > +++ b/net/sunrpc/svc_xprt.c > @@ -651,18 +651,10 @@ static void svc_check_conn_limits(struct svc_serv *= serv) > =20 > static bool svc_alloc_arg(struct svc_rqst *rqstp) > { > - struct svc_serv *serv =3D rqstp->rq_server; > struct xdr_buf *arg =3D &rqstp->rq_arg; > unsigned long pages, filled, ret; > =20 > - pages =3D (serv->sv_max_mesg + 2 * PAGE_SIZE) >> PAGE_SHIFT; > - if (pages > RPCSVC_MAXPAGES) { > - pr_warn_once("svc: warning: pages=3D%lu > RPCSVC_MAXPAGES=3D%lu\n", > - pages, RPCSVC_MAXPAGES); > - /* use as many pages as possible */ > - pages =3D RPCSVC_MAXPAGES; > - } > - > + pages =3D rqstp->rq_maxpages; > for (filled =3D 0; filled < pages; filled =3D ret) { > ret =3D alloc_pages_bulk(GFP_KERNEL, pages, rqstp->rq_pages); > if (ret > filled) > diff --git a/net/sunrpc/xprtrdma/svc_rdma_rw.c b/net/sunrpc/xprtrdma/svc_= rdma_rw.c > index 40797114d50a..661b3fe2779f 100644 > --- a/net/sunrpc/xprtrdma/svc_rdma_rw.c > +++ b/net/sunrpc/xprtrdma/svc_rdma_rw.c > @@ -765,7 +765,7 @@ static int svc_rdma_build_read_segment(struct svc_rqs= t *rqstp, > } > len -=3D seg_len; > =20 > - if (len && ((head->rc_curpage + 1) > ARRAY_SIZE(rqstp->rq_pages))) > + if (len && ((head->rc_curpage + 1) > rqstp->rq_maxpages)) > goto out_overrun; > } > =20 nit: I'd probably squash 2 and 3 together, but they both look right: Reviewed-by: Jeff Layton